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M. J. Root*, M. S. Kay, and P. S. Kim
Whitehead Inst. for Biomed. Res., Massachusetts Inst. of Technology, Cambridge
Background: HIV-1 cellular entry is promoted by the formation of a trimer-of-hairpins structure that serves to bring the N- and C-terminal regions of the gp41 ectodomain into close proximity, thereby facilitating membrane fusion. Peptides derived from the C-terminal region (C-peptides) potently inhibit HIV-1 entry by binding to the gp41 N-terminal region. To test the converse of this inhibitory strategy, we designed a small protein, denoted 5-Helix, that binds the C-peptide region of gp41.
Methods: 5-Helix was engineered to contain five of the sixa-helices that make up the core of the gp41 trimer-of-hairpins structure. 5-Helix lacks a third C-peptide helix, and this vacancy is expected to create a high-affinity binding site for the C-terminal region of gp41.
Results: 5-Helix is well-folded and extremely stable, with ana-helical content in agreement with the value predicted from the design. The protein interacts strongly and specifically with C-peptides and is capable of precipitating gp41 from cellular surfaces. 5-Helix displays potent (nanomolar) inhibitory activity against diverse HIV-1 variants in vitro .
Conclusion: These results point to the C-peptide region of HIV-1 gp41 as a viable target to inhibit the formation of the trimer-of-hairpins, and may serve as the basis for the development of a new class of antiviral agents. The inhibitory activity of 5-Helix also suggests that C-peptides, constrained in a helical conformation, might be useful immunogens for generating a neutralizing antibody response.
© 8th Conference on Retroviruses and Opportunistic Infections